The present invention generally relates to lasers and, more particularly, to a mechanism for adjustably aligning a laser mirror to its proper precise position for producing optimum lasing action.
A conventional gas discharge laser, such as a helium-neon gas laser, typically includes an outer envelope which mounts components at its opposite ends defining an anode and a cathode. End mirrors are mounted adjacent opposite ends of the envelope by the anode and cathode components, and a bore tube is mounted within the envelope and in alignment with the end mirrors. To form an optical resonant cavity and produce optimum lasing action, the bore tube and end mirrors must be precisely aligned along a common, central axis.
Adjustment of mirror alignment is made possible by the arrangement in which the mirrors are mounted at the ends of the laser envelope. For instance, with regard to the mounting arrangement of the cathode mirror in a typical laser construction, the cathode components include a cathode end cap attached to one end of the outer envelope of the laser and a cathode post electrically and mechanically connected thereto. The cathode end cap has a central opening and the cathode post is fixed at its inner end to the cathode end cap such that its central passage is coaxially aligned through the end cap opening with the central axis of the laser. The cathode mirror is mounted to the outer end of the cathode post, such as being adhesively bonded thereto, so as to extend generally perpendicular to the central axis of the laser.
Generally speaking, alignment of the cathode mirror is typically carried out empirically by a technician during production of the laser. The laser is placed in a test fixture and activated to an operating state. The technician then manually adjusts the angular position of the mirror by bending the cathode post until the laser is operating in an acceptable fashion.
Ordinarily, the technician bends the cathode post in one of two ways. The first way is a rather crude technique in which the cathode post is angularly deformed using a screwdriver. The second way is somewhat more refined. It uses a series of screws threaded into a plate attached to the inner end of the cathode post. The screws are threaded through holes in the plate so as to extend in generally parallel relation to the central axis and are pressed in contact against the cathode end cap. The technician threads selected ones of the screws toward the cathode end cap to cause the desired degree of tilting of the plate and cathode post and thereby the desired amount of angular adjustment of the cathode mirror with respect to the central axis.
The above-described techniques are simply too crude and unrefined to provide the degree of control over the adjustment process necessary to achieve the level of precision in mirror alignment desired for optimum laser performance. Consequently, a need still remains for an improved approach to precise alignment of the laser mirrors.